Field of the Invention
The present invention relates to a sheet feeding apparatus for feeding a sheet used in an image forming apparatus such as a multifunction peripheral and a printer.
Description of the Related Art
A sheet feeding apparatus used in an image forming apparatus such as a printer generally feeds an uppermost sheet of sheets stacked on a sheet stacking tray one by one. In this regard, a sheet remaining amount in a sheet feeding cassette may be detected in order to notify a user of the sheet remaining amount in the sheet feeding cassette and prompt the user to supply sheets. There are some conventional discussions about detection of a sheet remaining amount. For example, according to Japanese Patent Application Laid-Open No. 10-007291, an encoder is disposed in a rotation unit of a lift motor for a sheet lift operation, and a slit of the encoder is measured by a sensor to detect the number of stacked sheets from pulse numbers (a rotation angle and a moving amount) from the sensor when the lift motor rotates.
According to Japanese Patent Application Laid-Open No. 2014-5122, a mechanism in which a interrupting plate linearly moves in conjunction with a lift of sheets to interrupt a sensor and a plurality of sensors for detecting a position of the interrupting plate are constituted. The number of stacked sheets is detected by the number of the sensors interrupted by the interrupting plate.
However, the technique described in Japanese Patent Application Laid-Open No. 10-007291 requires an encoder and the like because continuous monitoring is necessary to measure a moving amount, and there is an issue that an increase in the number of parts increases a cost. The technique described in Japanese Patent Application Laid-Open No. 2014-5122 can downsize a configuration around the sensor, however gears and pulleys are necessary to be included in an entire apparatus. In addition, a flag for interrupting light in the sensor needs to be designed in a large size to interrupt a plurality of sensors so as not to cause a sensor transition state, which makes an apparatus size complicated and large.